attribute vec4 a_position; 
attribute vec2 a_texCoord0;

uniform mat4 u_projectionViewMatrix;

varying vec2 v_texCoords;
varying vec4 v_screenCoords;
void main()
{
	v_texCoords = a_texCoord0; 	
	v_screenCoords = u_projectionViewMatrix * a_position; 
	gl_Position = v_screenCoords;
	v_screenCoords.xy += v_screenCoords.w;
	v_screenCoords.xy *=0.5;
}